Has anyone just "known" they were pregnant before? Long before a test?

I know it seems silly but I'm wondering if anyone has ever had unprotected sex and started symptoms not long after that weren't usual for their ovulation days and periods...have you ever taken a PT and looked back and thought you had noticed subtle changes before the missed period? Some people are really in tune with their bodies so I was curious if anyone can remember feeling "off" before they had a clue